Lysimachia nummularia
A low, spreading herbaceous groundcover reaching only 2 to 4 inches tall while trailing 12 to 18 inches, with rounded coin-shaped leaves on stems that root readily at the nodes. It prefers part to full shade and consistently moist soil, performing best in damp or boggy ground and along water features rather than in dry, low-water settings. Cup-shaped yellow flowers appear in early summer above the bright green to chartreuse foliage. Use it as a moist-area groundcover, for softening pond and stream margins, between stepping stones, and as a spiller where reliable irrigation is available; note that it can spread vigorously in favorable conditions.